You say Aubergine, I say Eggplant

Considered a native of India, aubergines are a warm-season crop that can be a challenge to grow in the British climate. They are better suited to the cloistered environment of an unheated greenhouse, tunnel or conservatory, though some varieties might be worth trying outdoors in the southern part of Britain.

Aubergines have showy purple flowers

Propagating

The earliest sowing can be made from the beginning of March onwards for crops that are to be grown in a greenhouse or tunnel. To start propagation,seeds can be broadcast into a flat tray filled with fine-grade compost, and then covered to a depth of 5–6mm. As another option, seeds can be sown into modules, sowing two seeds per cell and removing the weaker seedling if both seeds germinate. Seed germination is optimum at temperatures between 24º and 32º C. Light is not required for germination, but must be provided as soon as the seedlings emerge.

After germination, seedlings started in seed trays should be pricked-out and replanted into 9cm pots when two true leaves have developed. However, seedlings grown in modules can be transferred, compost and all, into pots at a later date when the cells are filled with roots.

Once germination is complete, the ambient temperature around the seedlings should be kept at a constant 21º C both day and night. Alternatively, it can be fluctuated between a high of 19–22º C during the day and a low of 16–19º C at night. These are guidelines only, and some deviation is not disastrous.Day temperatures of up to 27º C, for example, will not harm the seedlings, and may even speed up their development. In contrast, lower temperatures will slow down growth, lengthening the time it takes the seedlings to reach transplant size.

As the seedlings grow, they will need to be fed a complete liquid fertiliser at least once to replace nutrients lost from the compost. In all, it takes about 8 weeks or more from sowing to producing a transplant, with the exact length of time affected by the light and heat levels available during propagation.

Growing on

Ideally, the transplants will be ready for planting-out from the beginning of May. Aubergines are best when grown in the ground, especially if it is well-drained with a pH between 5.5 and 7.5. Plants should be spaced 45–60 cm apart. If fertility levels are low, a solid complete fertiliser should be incorporated just before planting.

Transplanting an aubergine plant

They can also be grown in growbags or compost-filled pots. Pots should be about 7.5 litres in size, though both larger (up to 15 litres) and smaller (as small as 5 litres) will do.

After they are transplanted, the plants can be left on their own to develop naturally. Such a laissez faire approach suits most aubergines and is perfect for short-statured varieties such as ‘Calliope’. With some extra management, however, a plant’s natural shape and size can be changed. For example, pinching off the growing tips when the main stems are at least 20cm tall encourages branching and the development of a bushy growth habit. Alternatively, the plants can be pruned and trained like indeterminate tomatoes, resulting in tidier plants that can be squeezed closer together.

Growing aubergines in pots (left) and in the ground (right)

However the plants are managed, they will need to be supported as they get larger and produce fruit. One way to do this, especially for shorter aubergines raised in the ground or pots, is by enclosing them in a tripod of bamboo canes. String can then be tied between the canes to give further support to the branches inside.

Watering should be done regularly, and the tunnel or greenhouse should be ventilated on sunny days. Plants grown in well-composted and fertilised soil may need no further nutrient supplementation. Those grown in growbags and pots, however, will have to be fed a complete liquid fertiliser every week or so when the nutrients get low – starting perhaps the first month after transplanting.

Pests and diseases

Garden-grown aubergines are quite disease free. They are, however, susceptible to attack by aphids and red spider mites, though both pests can be controlled by either predators or pesticides. Alternatively, small aphid infestations can be rubbed off with the fingers or washed off, and misting the leaves with water may increase humidity to the point where red spider mite damage is reduced.

Harvesting

Aubergines should be ready to harvest as early as the latter part of July. They are, however, past their best when the skin loses its gloss and the seeds turn dark and hard, and getting the harvest time right is simply a matter of experience. Because of their tough pedicels, fruits must be harvested with a knife or secateurs.

Though aubergines do not have the universal appeal of tomatoes, they are the ideal addition to the edible repertoire of any gardener wanting to try something exotic. They need more heat and care than many vegetables, but their usefulness in the kitchen makes the extra effort worthwhile.